EN 60068-2-41:1999

SLOVENSKI STANDARD
01-september-2001
Environmental testing - Part 2: Tests - Test Z/BM: Combined dry heat/low air
pressure tests
Environmental testing -- Part 2: Tests - Test Z/BM: Combined dry heat/low air pressure
tests
Umweltprüfungen -- Teil 2: Prüfungen - Prüfung Z/BM: Kombinierte Prüfung - Trockene
Wärme/Niedriger Luftdruck
Essais d'environnement -- Partie 2: Essais - Essai Z/BM: Essais combinés chaleur
sèche/basse pression atmosphérique
Ta slovenski standard je istoveten z: EN 60068-2-41:1999
ICS:
19.040 Preskušanje v zvezi z Environmental testing
okoljem
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

NORME CEI
INTERNATIONALE
IEC
60068-2-41
INTERNATIONAL
Première édition
STANDARD
First edition
1976-01
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ
Essais fondamentaux climatiques
et de robustesse mécanique –
Partie 2-41:
Essais – Essai Z/BM: Essais combinés chaleur
sèche/basse pression atmosphérique

Basic environmental testing procedures
Part 2-41:
Tests – Test Z/BM: Combined dry heat/low air
pressure tests
CODE PRIX
K
Commission Electrotechnique Internationale
PRICE CODE
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
Pour prix, voir catalogue en vigueur

CONTENTS
Page
FOREWORD 5
PREFACE 5
Clause
1. Introduction
1.1 General
1.2 Low air pressure
1.3 Temperature
7 1.4 Related documents
2. Object 9
General description 3.
4. Description of test apparatus
4.1 Test chamber
4.2 Mounting
5. Severities
5.1 General
5.2 Preferred combinations of temperature, air pressure and duration 9
6. Preconditioning
Initial measurements 7.
8. Conditioning
8.1 General
8.2 Procedure for heat-dissipating specimen without artificial cooling of the specimen and for non-heat-
dissipating specimen
8.3 Precautions when testing specimens with artificial cooling
Intermediate measurements 13
9.
10. Recovery
Final measurements 13
11.
12. Information to be given in the relevant specification
17-19
FIGURES
– 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
–––––––––
BASIC ENVIRONMENTAL TESTING PROCEDURES –
Part 2: Tests – Test Z/BM: Combined dry heat/low air pressure tests
FOREWORD
1) The formal decisions or agreements of the IEC on technical matters, prepared by technical committees on
which all the National Committees having a special interest therein are represented, express, as nearly as
possible, an international consensus of opinion on the subjects dealt with.
2) They have the form of recommendations for international use and they are accepted by the National
Committees in that sense.
3) In order to promote international unification, the IEC expresses the wish that all National Committees should
adopt the text of the IEC recommendation for their national rules in so far as national conditions will permit. Any
divergence between the IEC recommendation and the corresponding national rules should, as far as possible,
be clearly indicated in the latter.
PREFACE
This publication has been prepared by subcommittee 50B: Climatic tests, of IEC technical
committee 50: Environmental testing.
A first draft was discussed at the meeting held in Munich in 1973. As a result of this meeting,
a Secretariat draft was submitted to the National Committees under the Accelerated
Procedure and submitted for approval under the Six Months' Rule as Document 50B(Central
Office)180 in September 1974.
It has the status of a basic safety publication in accordance with IEC Guide 104.
The following countries voted explicitly in favour of publication:
Australia Norway
Austria Poland
Belgium Portugal
Canada South Africa (Republic of)
Czechoslovakia Spain
Denmark Sweden
France Switzerland
Germany Turkey
Hungary Union of Soviet Socialist Republics
Netherlands United Kingdom
BASIC ENVIRONMENTAL TESTING PROCEDURES
Part 2: Tests — Test Z/BM:
Combined dry heat/low air pressure tests
1. Introduction
1.1 General
This publication deals with combined dry heat (with gradual change of temperature) and low air pressure tests
for both heat-dissipating and non-heat-dissipating specimens.
The object of the test is to determine the ability of components or equipments or other articles to be stored and
used under a simultaneous combination of high temperature and low air pressure.
This combined test should normally be used only if the effects of combined environments will not be revealed
by subjecting the specimen to single environments. The procedures given in this publication are limited to the
case of specimens which achieve temperature stability during the test procedure.
In the case of testing heat-dissipating specimens, this procedure applies only to the testing of one specimen at
a time.
1.2 Low air pressure
The test procedure applies to air pressure down to about 10 mbar. At air pressures below 10 mbar, phenomena
not taken into account in the design of this test procedure become important.
The relationship between altitude, pressure and temperature has not been indicated in this publication. Such
data should be obtained from special publications.
1.3 Temperature
1.3.1 The guidance given in the introduction to I E C Publication 68-2-2, Tests B: Dry heat, for the application
of tests for non-heat-dissipating specimens versus tests for heat-dissipating specimens shall apply.
Note. — Non-heat-dissipating specimens are defined as in Clause 4 of Publication 68-1. The measurements of hottest spot temperature
must not be made at reduced pressure.
1.3.2 Heat-dissipating specimens should preferably be tested with no forced air circulation as for Tests B: Dry heat.
1.4 Related documents
Publication 68: — Basic Environmental Testing Procedures.
Publication 68-1: Part L General.
Publication 68-2-2: Part 2: Tests. Tests B: Dry Heat.
Tests. Test M: Low Air Pressure.
Publication 68-2-13: Part 2:
Part 3: Background Information. Section One: Cold and Dry Heat Tests.
Publication 68-3-1:
Part 3: Background Information. Section Two: Combined Temperature/Low Air Pressure
Publication 68-3 -2:
Tests.
— 9 —
2. Object
To provide a standard test procedure to determine the suitability of components, equipments or other articles
for use and/or storage under a combination of high temperature and low air pressure.
3. General description
Dry heat, and Test M: Low air pressure.
This test is a combination of Tests Bb or Bd:
The specimen is first subjected to the appropriate severity of dry heat as specified in the relevant specification.
In the case of operational tests, a check is then made to ensure that the specimen is capable of operation.
With the temperature maintained at the prescribed value, the chamber air pressure is then reduced to the appro-
priate severity as specified in the relevant specification. These conditions are maintained for the specified duration.
Test profiles illustrating the procedure are shown in Figures la, page 17, and lb, page 19.
4. Description of test apparatus
4.1 Test chamber
The chamber shall be capable of maintaining the conditions specified for Test Bb (for non-heat-dissipating
specimen) or Test Bd (for heat-dissipating specimen) and for Test M. The requirement for the chamber wall temp-
erature does not apply during periods of temperature or pressure change.
Care shall be taken to avoid air contamination by ancillary equipment and devices and by the air introduced
when pressure is restored to normal.
4.2 Mounting
For the testing of a heat-dissipating specimen, the mounting of the test specimen shall comply with the require-
ments of Test Bd.
5. Severities
5.1 General
The severities, as indicated by temperature, air pressure and duration of exposure, shall be specified in the
relevant specification.
The temperature and low air pressure values, tolerances and durations shall comply with those given 'in Tests Bb
or Bd and M. The wider tolerances on temperature (+3 °C up to 100 °C and +5 °C up to 200 °C) can be accepted
for the combined dry heat/low air pressure test regardless of the size of the chamber.
The duration of exposure shall be measured from the time when temperature stability of the specimen has been
reached under conditions of low air pressure (see Figures la, page 17, and lb, page 1
...